An in-vehicle speaker attached to a ceiling base material of an vehicle is known (see, for example. Japanese Patent Provisional Publication No. 2005-22546A hereafter referred to as “patent document 1”). The in-vehicle speaker of this type is configured such that a body part thereof attached to a ceiling base material functions as a vibrator, and sound is output by letting interior material, such as a ceiling material and a door trim, vibrate as a vibrating plate.